This invention is in the field of drilling, repair or maintenance of wells.
In the drilling, repair or maintenance of wells, particularly oil and gas wells, pipe is raised and lowered by cables mounted on derricks. A pipe or pipes may be lifted singly to be introduced into the wellbore, or a pipe or pipes may be lifted singly to be removed from the wellbore. Pipes may be connected n stands, consisting of two or more joints, and be lifted to be introduced to the well bore or lifted to be removed from the well bore, for example, during a tripping operation, where all of the pipe is removed from the well and then reinstalled back into the well, to replace, modify, maintain or repair some or all of, for example, the bottom hole assembly which may include several tools known to those skilled in the art, during which pipe may be removed, replaced or reinstalled. The pipe may be lowered either gradually, as during drilling, or may be lowered or raised more quickly during, for example, a tripping operation.
A deficiency in the raising and lowering of pipe in the operation of drilling, repair or maintenance of wells is the necessity to interrupt the raising or lowering operation in order to connect or disconnect pipe while removing or installing pipe, for example, during a tripping operation.